1. Field of the Invention
The present disclosure relates to welded assemblies, and more particularly to welded joints for coupling hot sheets and cold sheets such as in hot sections of gas turbine engines.
2. Description of Related Art
Gas turbine engine hot section interiors can operate at extremely high temperatures. They typically include a liner that is directly exposed to a flow of hot combustion gases during engine operation for extended periods. The liner, i.e. a hot sheet, is typically a sheet metal structure surrounding the combustion flow space aft of where fuel and oxidizer flows are mixed and ignited prior to being passed to the turbine section. In certain engines an outer liner, e.g. a cold sheet, envelopes the hot sheet. The cold sheet is spaced away from the hot sheet such that a plenum is defined between the outer surface of the hot sheet and the inner surface of the cold sheet. Working fluid, typically air, is extracted from the compressor section of the engine and flows through the plenum between the cold sheet and the hot sheet for purpose cooling the hot sheet.
The hot sheet requires structure to fix the hot sheet within the engine. Generally, hot sheets couple to engine structure using sheet metal structures attached the hot sheet outer surface. In hot sections including cold sheet and hot sheet portions, these sheet metal structures extend through the plenum and form joints on opposite ends at the inner surface of the cold sheet and outer surface of the hot sheet. Because the stress imposed on the coupling structure, the respective joints on the cold sheet and hot ends are generally formed by a brazing process. Due to extreme temperatures and materials from the cold, hot sheet, and coupling body are constructed theses brazes are typically relatively costly nickel or gold-nickel brazes.
Conventional brazed joints have generally been considered satisfactory for their intended purpose. However, there is a continuing need to reduce cost and complexity of engine manufacture. There also remains a need for lightweight joints for applications such as those described above. The present disclosure provides a solution for these problems.